Demographic and clinical factors influence the metabolome. The discovery and validation of diseas... more Demographic and clinical factors influence the metabolome. The discovery and validation of disease biomarkers are often challenged by potential confounding effects from such factors. To address this challenge, we investigated the magnitude of the correlation between serum and urine metabolites and demographic and clinical parameters in a well-characterized observational cohort of 444 post-menopausal women participating in the Women’s Health Initiative (WHI). Using LC-MS and lipidomics, we measured 157 aqueous metabolites and 756 lipid species across 13 lipid classes in serum, along with 195 metabolites detected by GC-MS and NMR in urine and evaluated their correlations with 29 potential disease risk factors, including demographic, dietary and lifestyle factors, and medication use. After controlling for multiple testing (FDR < 0.01), we found that log-transformed metabolites were mainly associated with age, BMI, alcohol intake, race, sample storage time (urine only), and dietary s...
Cocoa flavanols may improve cardiometabolic health. Evidence from small short-term randomized cli... more Cocoa flavanols may improve cardiometabolic health. Evidence from small short-term randomized clinical trials (RCTs) remains inconsistent, and large long-term RCTs testing the efficacy of cocoa flavanols are still lacking. We performed a systematic review and meta-analysis of RCTs to quantify the effect of cocoa flavanol intake on cardiometabolic biomarkers. We searched PubMed, Web of Science, and the Cochrane Library for RCTs that evaluated the effects of cocoa flavanols on biomarkers relevant to vascular disease pathways among adults. Data were extracted following a standardized protocol. We used DerSimonian and Laird random-effect models to compute the weighted mean differences (WMDs) and 95% CIs. We also examined potential modification by intervention duration, design, age, sex, comorbidities, and the form and amount of cocoa flavanol intake. We included 19 RCTs that comprised 1131 participants, and the number of studies for a specific biomarker varied. The amount of cocoa flava...
Little is known about magnesium intake and risk of heart failure (HF) hospitalizations, particula... more Little is known about magnesium intake and risk of heart failure (HF) hospitalizations, particularly in blacks. We hypothesize that magnesium intake relates to HF hospitalization in blacks. From the Jackson Heart Study cohort (n=5301), we studied 4916 blacks recruited during 2000 to 2004 in Jackson (Mississippi), who completed an 158-item Food-Frequency Questionnaire that included dietary supplements. Daily magnesium intake derived from the questionnaire was divided by the body weight to account for body storage and stratified by quartiles (0.522-2.308, 2.309-3.147, 3.148-4.226, and ≥4.227 mg magnesium intake/kg). Cox proportional hazards modeling assessed the association between quartiles of magnesium intake/kg and hospitalizations for HF adjusting for HF risk, energy intake, and dietary factors. The cohort had a mean age=55.3 (SD=12.7 years) and composed of 63.4% women, 21.6% diabetes mellitus, 62.7% hypertension, 7.1% coronary disease, and 2.8% with known HF. When compared with p...
Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases;... more Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases; however, there are no comprehensive and quantitative assessments of available data in humans. The aim of this study was to systematically examine longitudinal studies investigating whole-grain and fiber intake in relation to risk of type 2 diabetes (T2D), cardiovascular disease (CVD), weight gain, and metabolic risk factors. We identified 45 prospective cohort studies and 21 randomized-controlled trials (RCT) between 1966 and February 2012 by searching the Cumulative Index to Nursing and Allied Health Literature, Cochrane, Elsevier Medical Database, and PubMed. Study characteristics, whole-grain and dietary fiber intakes, and risk estimates were extracted using a standardized protocol. Using random effects models, we found that compared with never/rare consumers of whole grains, those consuming 48-80 g whole grain/d (3-5 serving/d) had an ~26% lower risk of T2D [RR = 0.74 (95% CI: 0.69,...
Rheumatoid arthritis (RA) patients have an increased risk of cardiovascular disease (CVD) and mor... more Rheumatoid arthritis (RA) patients have an increased risk of cardiovascular disease (CVD) and mortality. We measured anti-cyclic citrullinated peptide (anti-CCP) antibody levels and determined use of disease-modifying antirheumatic drugs (DMARDs) among women in the Women's Health Initiative (WHI). Using these data, we undertook this study to assess total mortality over 10 years of followup among white, black, or Hispanic women with self-reported RA in the WHI. Using stored baseline serum, we measured anti-CCP, rheumatoid factor (RF), and antinuclear antibodies (ANAs) in 9,988 women who reported having RA. Based on a previous chart review study, probable RA was defined as either self-reported RA and anti-CCP positivity, or anti-CCP negativity and DMARD use. Cox proportional hazards regression was used to model the relationship of self-reported RA, DMARD exposure, and anti-CCP positivity to total mortality, using followup data through April 2009. At baseline, the mean age was 62.8...
Cancer Epidemiology, Biomarkers & Prevention, 2008
Recent genome-wide association studies identified key single nucleotide polymorphisms (SNPs) in t... more Recent genome-wide association studies identified key single nucleotide polymorphisms (SNPs) in the 8q24 region to be associated with prostate cancer. 8q24 SNPs have also been associated with colorectal cancer, suggesting that this region may not be specifically associated to just prostate cancer. To date, the association between these polymorphisms and tobacco smoking-related cancer sites remains unknown. Using epidemiologic data and biological samples previously collected in three case-control studies from U.S. and Chinese populations, we selected and genotyped one SNP from each of the three previously determined “regions” within the 8q24 loci, rs1447295 (region 1), rs16901979 (region 2), and rs6983267 (region 3), and examined their association with cancers of the lung, oropharynx, nasopharynx, larynx, esophagus, stomach, liver, bladder, and kidney. We observed noteworthy associations between rs6983267 and upper aerodigestive tract cancers [adjusted odds ratio (ORadj), 1.69; 95% c...
Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in ... more Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in two Alabama areas after tornado warnings. In the area without sirens, only 28.9% of 194 respondents heard a tornado warning of these, 73.2% first received the warning from radios or television. In the area with sirens, 88.1% of 193 respondents heard a warning, and 61.8% first received the warning from a siren. Knowledge of warnings, access to shelter, and education were key predictors for seeking shelter. Our findings indicate that installing sirens, providing access to shelter, and teaching appropriate responses to warnings are important elements of an effective disaster prevention system.
OBJECTIVES. This study investigated patterns of and risk factors for smoking among elementary sch... more OBJECTIVES. This study investigated patterns of and risk factors for smoking among elementary school children in Beijing, China. METHODS. In 1988, anonymous questionnaires were administered to a multistage stratified cluster sample of 16996 students, aged mostly 10 to 12, in 479 fourth- to sixth-grade classes from 122 Beijing elementary schools. RESULTS. Approximately 28% of boys and 3% of girls had smoked cigarettes. The most frequently cited reasons for smoking initiation were "to imitate others' behavior" and "to see what it was like." Girls were more likely to get cigarettes from home than to purchase their own. Having close friends who smoked and being encouraged by close friends to smoke were strong risk factors for smoking. Smoking was also associated with lower parental socioeconomic status; having parents, siblings, or teachers who smoked; buying cigarettes for parents; performing poorly in school; and not believing that smoking is harmful to health....
OBJECTIVES: This study examined the association between intake of whole vs refined grain and the ... more OBJECTIVES: This study examined the association between intake of whole vs refined grain and the risk of type 2 diabetes mellitus. METHODS: We used a food frequency questionnaire for repeated dietary assessments to prospectively evaluate the relation between whole-grain intake and the risk of diabetes mellitus in a cohort of 75,521 women aged 38 to 63 years without a previous diagnosis of diabetes or cardiovascular disease in 1984. RESULTS: During the 10-year follow-up, we confirmed 1879 incident cases of diabetes mellitus. When the highest and the lowest quintiles of intake were compared, the age and energy-adjusted relative risks were 0.62 (95% confidence interval [CI] = 0.53, 0.71, P trend < .0001) for whole grain, 1.31 (95% CI = 1.12, 1.53, P trend = .0003) for refined grain, and 1.57 (95% CI = 1.36, 1.82, P trend < .0001) for the ratio of refined- to whole-grain intake. These findings remained significant in multivariate analyses. The findings were most evident for women ...
Demographic and clinical factors influence the metabolome. The discovery and validation of diseas... more Demographic and clinical factors influence the metabolome. The discovery and validation of disease biomarkers are often challenged by potential confounding effects from such factors. To address this challenge, we investigated the magnitude of the correlation between serum and urine metabolites and demographic and clinical parameters in a well-characterized observational cohort of 444 post-menopausal women participating in the Women’s Health Initiative (WHI). Using LC-MS and lipidomics, we measured 157 aqueous metabolites and 756 lipid species across 13 lipid classes in serum, along with 195 metabolites detected by GC-MS and NMR in urine and evaluated their correlations with 29 potential disease risk factors, including demographic, dietary and lifestyle factors, and medication use. After controlling for multiple testing (FDR < 0.01), we found that log-transformed metabolites were mainly associated with age, BMI, alcohol intake, race, sample storage time (urine only), and dietary s...
Cocoa flavanols may improve cardiometabolic health. Evidence from small short-term randomized cli... more Cocoa flavanols may improve cardiometabolic health. Evidence from small short-term randomized clinical trials (RCTs) remains inconsistent, and large long-term RCTs testing the efficacy of cocoa flavanols are still lacking. We performed a systematic review and meta-analysis of RCTs to quantify the effect of cocoa flavanol intake on cardiometabolic biomarkers. We searched PubMed, Web of Science, and the Cochrane Library for RCTs that evaluated the effects of cocoa flavanols on biomarkers relevant to vascular disease pathways among adults. Data were extracted following a standardized protocol. We used DerSimonian and Laird random-effect models to compute the weighted mean differences (WMDs) and 95% CIs. We also examined potential modification by intervention duration, design, age, sex, comorbidities, and the form and amount of cocoa flavanol intake. We included 19 RCTs that comprised 1131 participants, and the number of studies for a specific biomarker varied. The amount of cocoa flava...
Little is known about magnesium intake and risk of heart failure (HF) hospitalizations, particula... more Little is known about magnesium intake and risk of heart failure (HF) hospitalizations, particularly in blacks. We hypothesize that magnesium intake relates to HF hospitalization in blacks. From the Jackson Heart Study cohort (n=5301), we studied 4916 blacks recruited during 2000 to 2004 in Jackson (Mississippi), who completed an 158-item Food-Frequency Questionnaire that included dietary supplements. Daily magnesium intake derived from the questionnaire was divided by the body weight to account for body storage and stratified by quartiles (0.522-2.308, 2.309-3.147, 3.148-4.226, and ≥4.227 mg magnesium intake/kg). Cox proportional hazards modeling assessed the association between quartiles of magnesium intake/kg and hospitalizations for HF adjusting for HF risk, energy intake, and dietary factors. The cohort had a mean age=55.3 (SD=12.7 years) and composed of 63.4% women, 21.6% diabetes mellitus, 62.7% hypertension, 7.1% coronary disease, and 2.8% with known HF. When compared with p...
Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases;... more Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases; however, there are no comprehensive and quantitative assessments of available data in humans. The aim of this study was to systematically examine longitudinal studies investigating whole-grain and fiber intake in relation to risk of type 2 diabetes (T2D), cardiovascular disease (CVD), weight gain, and metabolic risk factors. We identified 45 prospective cohort studies and 21 randomized-controlled trials (RCT) between 1966 and February 2012 by searching the Cumulative Index to Nursing and Allied Health Literature, Cochrane, Elsevier Medical Database, and PubMed. Study characteristics, whole-grain and dietary fiber intakes, and risk estimates were extracted using a standardized protocol. Using random effects models, we found that compared with never/rare consumers of whole grains, those consuming 48-80 g whole grain/d (3-5 serving/d) had an ~26% lower risk of T2D [RR = 0.74 (95% CI: 0.69,...
Rheumatoid arthritis (RA) patients have an increased risk of cardiovascular disease (CVD) and mor... more Rheumatoid arthritis (RA) patients have an increased risk of cardiovascular disease (CVD) and mortality. We measured anti-cyclic citrullinated peptide (anti-CCP) antibody levels and determined use of disease-modifying antirheumatic drugs (DMARDs) among women in the Women's Health Initiative (WHI). Using these data, we undertook this study to assess total mortality over 10 years of followup among white, black, or Hispanic women with self-reported RA in the WHI. Using stored baseline serum, we measured anti-CCP, rheumatoid factor (RF), and antinuclear antibodies (ANAs) in 9,988 women who reported having RA. Based on a previous chart review study, probable RA was defined as either self-reported RA and anti-CCP positivity, or anti-CCP negativity and DMARD use. Cox proportional hazards regression was used to model the relationship of self-reported RA, DMARD exposure, and anti-CCP positivity to total mortality, using followup data through April 2009. At baseline, the mean age was 62.8...
Cancer Epidemiology, Biomarkers & Prevention, 2008
Recent genome-wide association studies identified key single nucleotide polymorphisms (SNPs) in t... more Recent genome-wide association studies identified key single nucleotide polymorphisms (SNPs) in the 8q24 region to be associated with prostate cancer. 8q24 SNPs have also been associated with colorectal cancer, suggesting that this region may not be specifically associated to just prostate cancer. To date, the association between these polymorphisms and tobacco smoking-related cancer sites remains unknown. Using epidemiologic data and biological samples previously collected in three case-control studies from U.S. and Chinese populations, we selected and genotyped one SNP from each of the three previously determined “regions” within the 8q24 loci, rs1447295 (region 1), rs16901979 (region 2), and rs6983267 (region 3), and examined their association with cancers of the lung, oropharynx, nasopharynx, larynx, esophagus, stomach, liver, bladder, and kidney. We observed noteworthy associations between rs6983267 and upper aerodigestive tract cancers [adjusted odds ratio (ORadj), 1.69; 95% c...
Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in ... more Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in two Alabama areas after tornado warnings. In the area without sirens, only 28.9% of 194 respondents heard a tornado warning of these, 73.2% first received the warning from radios or television. In the area with sirens, 88.1% of 193 respondents heard a warning, and 61.8% first received the warning from a siren. Knowledge of warnings, access to shelter, and education were key predictors for seeking shelter. Our findings indicate that installing sirens, providing access to shelter, and teaching appropriate responses to warnings are important elements of an effective disaster prevention system.
OBJECTIVES. This study investigated patterns of and risk factors for smoking among elementary sch... more OBJECTIVES. This study investigated patterns of and risk factors for smoking among elementary school children in Beijing, China. METHODS. In 1988, anonymous questionnaires were administered to a multistage stratified cluster sample of 16996 students, aged mostly 10 to 12, in 479 fourth- to sixth-grade classes from 122 Beijing elementary schools. RESULTS. Approximately 28% of boys and 3% of girls had smoked cigarettes. The most frequently cited reasons for smoking initiation were "to imitate others' behavior" and "to see what it was like." Girls were more likely to get cigarettes from home than to purchase their own. Having close friends who smoked and being encouraged by close friends to smoke were strong risk factors for smoking. Smoking was also associated with lower parental socioeconomic status; having parents, siblings, or teachers who smoked; buying cigarettes for parents; performing poorly in school; and not believing that smoking is harmful to health....
OBJECTIVES: This study examined the association between intake of whole vs refined grain and the ... more OBJECTIVES: This study examined the association between intake of whole vs refined grain and the risk of type 2 diabetes mellitus. METHODS: We used a food frequency questionnaire for repeated dietary assessments to prospectively evaluate the relation between whole-grain intake and the risk of diabetes mellitus in a cohort of 75,521 women aged 38 to 63 years without a previous diagnosis of diabetes or cardiovascular disease in 1984. RESULTS: During the 10-year follow-up, we confirmed 1879 incident cases of diabetes mellitus. When the highest and the lowest quintiles of intake were compared, the age and energy-adjusted relative risks were 0.62 (95% confidence interval [CI] = 0.53, 0.71, P trend < .0001) for whole grain, 1.31 (95% CI = 1.12, 1.53, P trend = .0003) for refined grain, and 1.57 (95% CI = 1.36, 1.82, P trend < .0001) for the ratio of refined- to whole-grain intake. These findings remained significant in multivariate analyses. The findings were most evident for women ...
Uploads
Papers by Simin Liu